15 This indeed is the very thing which Paul rebukes, when he says, “And do you think this, O man, that judgest them which do such things, and doest the same, that you shall escape the judgment of God?” It is not, it cannot be possible; for from the very sentence, he means, which you pronounce upon another, from this sentence God will then judge you. For surely you are not just, and God unjust! But if you overlook not another suffering wrong, how shall God overlook?
And if you correct the sins of others, how will not God correct you? And though He may not bring the punishment upon you instantly, be not confident on that account, but fear the more. So also Paul bade you, saying, “Despisest thou the riches of His goodness, and forbearance, and longsuffering, not knowing that the goodness of God leads you to repentance?” For therefore, says he, does he bear with you, not that you may become worse, but that you may repent. But if you will not, this longsuffering becomes a cause of your greater punishment; continuing, as you do, impenitent.
This, however, is the very thing he means, when he says, “But after your hardness and impenitent heart treasurest up to yourself wrath against the day of wrath, and revelation of the righteous judgment of God. Who will render to every man according to his deeds.” Since, therefore, He renders to every man according to his works; for this reason He both implanted within us a natural law, and afterwards gave us a written one, in order that He might demand an account of sins, and that He might crown those who act rightly. Let us then order our conduct with the utmost care, and as those who have soon to encounter a fearful tribunal; knowing that we shall enjoy no pardon, if after a natural as well as written law, and so much teaching and continual admonition, we neglect our own salvation.
Source: Homilies on the Statues (New Advent)